Program TB_Cong_4_So;

uses crt;

Var a, b, c, d: real;

Begin

     Clrscr;

     Write('Nhap so thu nhat:');readln(a);

     Write('Nhap so thu hai:');readln(b);

     Write('Nhap so thu ba:');readln(c);

     Write('Nhap so thu tu:');readln(d);

     Writeln('Trung binh cong: ',(a+b+c+d)/4):10:2);